Julesmusician From , joined Dec 1969, posts, RR: Posted (7 years 4 months 1 week 18 hours ago) and read 3827 times:
Following the incident over London where a 747 was running with very little engine power there have been recommendations that all pilots should be aware of their no power gliding profile of their aircraft - is this every done in simulators or if this did happen is it always down to a pilot's skill?
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 1, posted (7 years 4 months 1 week 17 hours ago) and read 3815 times:
The commander carried out the descent using the autopilot in the vertical speed mode during which he became aware that the thrust levers were positioned in the “number six position”
What are the Thrust lever positions on a B747.
The crew discussed the anomaly of the forward thrust lever position and low engine power indications and recorded the engine EPRs as: ‘#1 eng 0.704, #2eng 1.124, #3eng 1.206 and #4eng 1.149’
Can EPR read less than 1.What stage are the EPR probes located on a B747
Fr8Mech From United States of America, joined Sep 2005, 4244 posts, RR: 12 Reply 4, posted (7 years 4 months 1 week 15 hours ago) and read 3774 times:
The EPR will less than 1.00 on descent.
The PT2 probe is located on the outboard side of the pylon. Left side for #1 & #2, right side for #3 & #4.
I've worked on the classics quite a bit, I believe I even worked N481EV, back in the day, and I've never heard of the '#6 throttle position'. He may have been referring to the index markings on the pedestal which are used by maintenance to mark throttle positions. 6 would have the throttle standing straight up, but nowhere near their max travel of about 11 or 12 (as I recall).
Interesting, according to the FDR graphic, the engines were stuck around the 1.15 - 1.21 range. This the 'bleed-shift' range (on the ground). As I recall, a JT9-7(x) that won't make power, but still has an increasing EGT, has not had 'bleed-shift'.
Bleed-shift is controlled on the engine independently of the other engines, except that one of th bleed controllers looks at air/ground logic. I just don;t remeber enough about chapter 75 on the JT9 to work it through my head any further.
PhilSquares From , joined Dec 1969, posts, RR: Reply 5, posted (7 years 4 months 1 week 13 hours ago) and read 3715 times:
The number 6 position is just the thrust lever markings on the throttle quadrant. They're used for rigging.
As a technique, I avoid using V/S because you can get slow very easy. In the older JT-9 engines, if you got slow it really took a good airflow through the fan to make sure the engine would accelerate. As Fr8Mech pointed out, there is a bleed shift issue and the older engines really suffer from those problems.
KJFK31L From United States of America, joined Jan 2006, 148 posts, RR: 0 Reply 6, posted (7 years 4 months 1 week 12 hours ago) and read 3650 times:
The report cited that the aircraft engines have a bleed air issue when the 747 is operating "light". It also indicates that the way to rectify such an issue is to power up the engine (to position 6). After 10 seconds the valve will reset itself and normal flight can be resumed.
Is this a common problem for 747-200 cargo aircraft operating with small cargo loads?
Fr8mech From United States of America, joined Sep 2005, 4244 posts, RR: 12 Reply 9, posted (7 years 4 months 6 days 13 hours ago) and read 3212 times:
Quoting HAWK21M (Reply 8): Any Pics on the Throttle Quadrant showing the Marks.
Mel,
It's just a scale on the throttle quandrant. There is a prominent mark at 3.7, which is the part-power rig point. This is the point where the cable system, from the pylon, down to the JFC is rigged.
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